This invention relates generally to transparencies, which transparencies are particularly useful in electrographic and xerographic imaging and printing processes. More specifically, the present invention is directed to transparencies with certain coatings thereover, which transparencies, that is for example transparent substrate materials for receiving or containing a toner image, possess compatibility with toner compositions, and permit improved toner flow in the imaged areas of the transparency thereby enabling images of high quality, that is for example images with optical densities of greater than 1.0 in several embodiments, excellent toner fix, about 100 percent in some instances, and no or minimized background deposits to be permanently formed thereon. Thus, in one embodiment of the present invention there are provided transparencies useful in electrophotographic including xerographic imaging systems, which transparencies are comprised of a supporting substrate, a first coating of, for example, an antistatic hydrophilic hydroxyethyl cellulose polymer layer present on one or both sides of the supporting substrate, and a second toner receiving coating thereover of a hydrophobic blend of, for example, ethylhydroxyethyl cellulose and an epichlorohydrin/ethylene oxide copolymer which blend can be present on one or both (two) sides of the antistatic layer, and wherein the second layer may contain optional filler components. Also, the present invention is directed to imaged transparencies comprised of a supporting substrate, a first antistatic coating of, for example, a hydrophilic cellulose derivative polymer layer present on one or on both (two) sides of the substrate, and a second toner receiving coating thereover comprised of a hydrophobic cellulose ether or cellulose esters with low melt adhesives, such as ethylene/vinyl acetate copolymers and poly(chloroprene) and wherein the second layer may contain optional filler components.
In the formation and development of xerographic images, there is generally applied to a latent image generated on a photoconductive member a toner composition comprised of resin particles and pigment particles. Thereafter, the image is transferred to a suitable substrate, and affixed thereto by, for example, heat, pressure, or a combination thereof. It is also known that transparencies can be selected as a receiver for the transferred developed image originating from the photoconductive member, which transparencies are suitable for selection with commercially available overhead projectors. Generally, these transparent sheets are comprised of thin films of one or more organic resins, such as polyesters, which have the disadvantage in that undesirable poor toner composition adhesion results in toner flaking off from the transparency.
In the Xerox Corporation 1005.TM. color imaging apparatus, a black color can be obtained from a combination of magenta, cyan and yellow pigments in three passes whereas in the Xerox Corporation 1025.TM. and 1075.TM. apparatuses this is achieved in one pass using carbon black based toners. Generally, the amount of the three pass images deposited toner layer of magenta, cyan, yellow to produce black, is greater than that of carbon black based toners deposited by single pass copiers. Thus the 1005.TM. apparatus (black) requires more heat to fuse the three layers together on substrates such as transparencies compared to pigmented black produced by the Xerox Corporation 1025.TM. or 1075.TM. apparatuses. Although these imaging apparatuses are equipped with variable fusing temperature options, there is an optimum temperature for maintaining an effective life span of the machine components; the lower the temperature, the longer the life span. To accommodate these transparency requirements, three pass color copiers are often decelerated in the transparency mode to generate extra heat for toner fusing. However, this extra heat is usually not sufficient to effectively fix the toner to the transparency, and the toners are fused by a post-solvent treatment in a solvent vapor-fuser. These problems are avoided or minimized with the transparencies of the present invention.
Many different types of transparencies are known, reference for example U.S. Pat. No. 3,535,112, which illustrates transparencies comprised of a supporting substrate, and polyamide overcoatings. Additionally, there are disclosed in U.S. Pat. No. 3,539,340 transparencies comprised of a supporting substrate and coatings thereover of vinylchloride copolymers. Also known are transparencies with overcoatings of styrene acrylate, or methacrylate ester copolymers, reference U.S. Pat. No. 4,071,362; transparencies with blends of acrylic polymers and vinyl chloride/vinylacetate polymers, as illustrated in U.S. Pat. No. 4,085,245; and transparencies with coatings of hydrophilic colloids as recited in U.S. Pat. No. 4,259,422. Furthermore, there is illustrated in U.S. Pat. Nos. (1) 4,489,122 transparencies with elastomeric polymers overcoated with poly(vinylacetate), or terpolymers of methylmethacrylate, ethyl acrylate, and isobutylacrylate; and (2) 4,526,847 transparencies comprised of overcoating of nitrocellulose and a plasticizer. The disclosures of each of the aforementioned patents are totally incorporated herein by reference.
In a patentability search report the following prior art U.S. Pat. Nos. were provided: 3,488,189 which discloses fused toner images on an imaging surface wherein the toner particles contain a thermoplastic resin, the imaging surface carries a solid crystalline plasticizer having a lower melting point than the melting range of the thermoplastic resin, and wherein the resulting toner image is heat fused, reference the abstract of the disclosure; see also columns 3,4, and 5 especially at line 71 to column 6; a similar teaching is present in U.S. Pat. No. 3,493,412, and U.S. Pat. No. 3,619,279, and more specifically the '279 patent mentions in the abstract that the external surfaces of the toner receiving member is substantially free of a material plasticizable by a solid crystalline plasticizer, and typically a plasticizer such as ethylene glycol dibenzoate may be available on the surface of the paper; further see column 3 lines 22 to 32 of the '279 patent for the types of receiving surfaces that may be treated; and a selection of patents, namely U.S. Pat. Nos. 3,535,112; 3,539,340; 3,539,341; 3,833,293; 3,854,942; 4,234,644; 4,259,422; 4,419,004; 4,419,005; and 4,480,003, that pertain to the preparation of transparencies by electrostatographic imaging techniques according to the aforementioned report.
Also known are transparency sheet materials for use in plain paper electrostatic copiers comprising (a) a flexible, transparent, heat resistant, polymeric film base, (b) an image receiving layer present upon a first surface of the film base, and (c) a layer of electrically conductive prime coat interposed between the image receiving layer and the film base. This sheet material can be used in either powder-toned or liquid-toned plain paper copiers for making transparencies, reference U.S. Pat. No. 4,711,816, the disclosure of which is totally incorporated herein by reference.
Additionally known is a transparency to be imaged as a copy sheet in plain paper copiers which transparency contains a transparent sheet having a surface adapted to receive an image imprinted thereon in a suitable electrostatic imaging apparatus and an opaque coating forming an opaque border completely around the sheet, reference U.S. Pat. No. 4,637,974, the disclosure of which is totally incorporated herein by reference.
Moreover known is the preparation of transparencies by electrostatic means, reference U.S. Pat. No. 4,370,379, the disclosure of which is totally incorporated herein by reference, wherein there is described the transferring of a toner image to a polyester film containing, for example, a substrate and a biaxially stretched poly(ethylene terephthalate) film, including Mylar. Furthermore, in U.S. Pat. No. 4,234,644, the disclosure of which is totally incorporated herein by reference, there is disclosed a composite lamination film for electrophoretically toned images deposited on a plastic dielectric receptor sheet comprising in combination an optically transparent flexible support layer, and an optically transparent flexible intermediate layer of a heat softenable film applied to one side of the support; and wherein the intermediate layer possesses adhesion to the support.
With further respect to the prior art, there are illustrated in U.S. Pat. No. 4,370,379, the disclosure of which is totally incorporated herein by reference, transparencies with, for example, a polyester (Mylar) substrate with a transparent plastic film substrate 2, and an undercoating layer 3 formed on at least one surface of the substrate 2, and a toner receiving layer 4 formed on the undercoated layer, reference column 2, line 44. As coatings for layer 3, there can be utilized the resins as illustrated in column 3, including quaternary ammonium salts, while for layer 4 there are selected thermoplastic resins having a glass transition temperature of from a minus 50.degree. to 150.degree. C., such as acrylic resins, including ethylacrylate, methylmethacrylate, and propyl methacrylate; and acrylic acid, methacrylic acid, maleic acids, and fumaric acid, reference column 4, lines 23 to 65. At line 61 of this patent, there is mentioned that thermoplastic resin binders other than acrylic resins can be selected, such as styrene resins, including polystyrene, and styrene butadiene copolymers, vinyl chloride resins, vinylacetate resins, and solvent soluble linear polyester resins. A similar teaching is present in U.S. Pat. No. 4,480,003 wherein there is disclosed a transparency film comprised of a film base coated with an image receiving layer containing thermoplastic transparent polymethacrylate polymers, reference column 2, line 16, which films are useful in plain paper electrostatic copiers. Other suitable materials for the image receiving layer include polyesters, cellulosics, poly(vinyl acetate), and acrylonitrile-butadiene-styrene terpolymers, reference column 3, lines 45 to 53. Similar teachings are present in U.S. Pat. No. 4,599,293, wherein there is described a toner transfer film for picking up a toner image from a toner treated surface, and affixing the image, wherein the film contains a clear transparent base and a layer firmly adhered thereto, which is also clear and transparent, and is comprised of the specific components as detailed in column 2, line 16. Examples of suitable binders for the transparent film that are disclosed in this patent include polymeric or prepolymeric substances, such as styrene polymers, acrylic, and methacrylate ester polymers, styrene butadienes, isoprenes, and the like, reference column 4, lines 7 to 39. The coatings recited in the aforementioned patents contain primarily amorphous polymers which do not undergo the desired softening during the fusing of the xerographic imaging processes such as the color process utilized in the Xerox Corporation 1005.TM., and therefore these coatings do not usually aid in the flow of pigmented toners. This can result in images of low optical density which are not totally transparent. In contrast with the coatings of the U.S. Pat. No. 4,956,225, the disclosure of which is totally incorporated herein by reference, which include, for example, polymers with a high degree of crystallinity and sharp melting points, there is enabled an increase in toner flow in the imaged areas thus yielding images, especially with mixed colors such as green, black and purple with acceptable optical density values.
More specifically there is described in the aforementioned U.S. Pat. No. 4,956,225, D/86267, transparencies suitable for electrographic and xerographic imaging comprised of a polymeric substrate with a toner receptive coating on one surface thereof, which coating is comprised of blends of: poly(ethylene oxide) and carboxymethyl cellulose; poly(ethylene oxide), carboxymethyl cellulose and hydroxypropyl cellulose; poly(ethylene oxide) and vinylidene fluoride/hexafluoropropylene copolymer, poly(chloroprene) and poly(.alpha.-methylstyrene); poly(caprolactone) and poly(.alpha.-methylstyrene); poly(vinylisobutylether) and poly(.alpha.-methylstyrene); blends of poly(caprolactone) and poly(.rho.-isopropyl .alpha.-methylstyrene); blends of poly(1,4-butylene adipate) and poly(.alpha.-methylstyrene); chlorinated poly(propylene) and poly(.alpha.-methylstyrene); chlorinated poly(ethylene) and poly(.alpha.-methylstyrene); and chlorinated rubber and poly(.alpha.-methylstyrene). Further, in another aspect of U.S. Pat. No. 4,956,225, the disclosure of which is totally incorporated herein by reference, there are provided transparencies suitable for electrographic and xerographic imaging processes comprised of a supporting polymeric substrate with a toner receptive coating on one surface thereof comprised of: (a) a first layer coating of a crystalline polymer selected from the group consisting of poly(chloroprene), chlorinated rubbers, blends of poly(ethylene oxide), and vinylidene fluoride/hexafluoropropylene copolymers, chlorinated poly(propylene), chlorinated poly(ethylene), poly(vinylmethyl ketone), poly(caprolactone), poly(1,4-butylene adipate), poly(vinylmethyl ether), and poly(vinyl isobutylether); and (b) a second overcoating layer comprised of a cellulose ether selected from the group consisting of hydroxypropyl methyl cellulose, hydroxypropyl cellulose, and ethyl cellulose.
Although the transparencies prepared with the coatings cited in the above mentioned U.S. Pat. No. 4,956,225 usually have higher optical densities than those obtained on commercially available (Xerox Corporation 3R2780) transparencies, when imaged with the Xerox Corporation 1005.TM. vapor fusing was necessary with for example, the apparatus commercially available from Xerox Corporation as the Xerox VFA for a period of 60 seconds with a solvent such as 1.1.1 trichloroethane to render them transparent. This disadvantage is avoided with the transparencies of the present invention.
Further, although the transparencies illustrated in the prior art are suitable in most instances for their intended purposes, there remains a need for new transparencies with coatings thereover, which transparencies are useful in electrophotographic and xerographic imaging processes, and that will enable the formation of images with high optical densities. Additionally, there is a need for transparencies which permit improved toner flow in the imaged areas thereby enabling high quality transparent images with acceptable optical densities. There is also a need for transparencies with specific coatings that possess other advantages, inclusive of enabling excellent adhesion between the toned image and the transparency or coated papers selected, and wherein images with excellent resolution and no background deposits are obtained. There is also a need for transparencies that can be used in more than one type of xerographic or electrophotographic apparatuses, as is the situation with the transparencies of the present invention. Another need of the present invention resides in providing transparencies with coatings that do not (block) stick at, for example, high relative humidities of, for example, 50 to 80 percent relative humidity and at a temperature of 50.degree. C. in many embodiments.